A. Field of the Invention
This invention relates in general to telemetry systems, and, in particular, a telemetry system for reporting actual or impending malfunctions of industrial equipment.
More specifically, but without restriction to the particular use which is shown and described, the invention relates to a telemetry system for reporting the status of a number of safety control and anticipatory control conditions of equipment being monitored during operation. One exemplary use of the invention of the application involves the monitoring of the operation of centrifugal water chilling systems and other refrigeration/air conditioning equipment.
In the operation of many types of industrial equipment and machinery, critical physical parameters are constantly or randomly evaluated to monitor performance of the system. In many situations, physical sensors are used to determine whether critical conditions deviate from an operative norm and may cause automatic shut-down of the equipment or transmit warning signals to operating personnel to effect whatever corrective action is needed. One type of system in which conditions are typically surveyed during operation is in conventional cooling systems, such as are used to control the internal environment of buildings and the like. For example, centrifugal water chilling systems often employ monitoring controls which act to shut-down the system for reasons of safety and protection of the equipment, if certain operative conditions critically deviate from acceptable norms. Such safety shut-down controls may generally be responsive to such factors as the thermal or pressure conditions in the evaporator or condenser of the chiller or to mechanical considerations associated with the compressor.
Prior art monitoring techniques employed in cooling systems and the like have been deficient in providing a truly effective telemetry system which is capable of automatically transmitting a coded identifying message over a telephone line and reporting the status of the various inputs to a special monitor receiver located at a remote location, either before or after actual shut-down. The transmission of anticipatory signals warning of impending system problems prior to actual shut-down is a particularly important consideration in cooling systems of buildings. The prompt transmittal of a warning message to a central station to alert service personnel offers the opportunity that the impending malfunction in the system be rectified before uneconomical and inconvenient termination of operation of the cooling system actually occurs in response to its safety control. Prior art telemetry systems have not satisfactorily been capable of transmitting coded messages to a remote monitoring station to warn that a condition in a cooling system is deviating from an acceptable level and that malfunctioning of the equipment is likely. Thus, known monitoring systems have not optimally provided constant surveilance of cooling equipment with the capability of promptly transmitting warning signals along with specific identification data to a remote location and permit responsive action to be taken to correct any problem which is detected.
B. Description of the Prior Art
An example of a centrifugal water chilling system with which the invention of the application may be used is disclosed in U.S. Pat. No. 4,151,725 to Kunz.